diff --git a/chain/consensus/filcns/upgrades.go b/chain/consensus/filcns/upgrades.go
index c1f594a92..3fa3dd995 100644
--- a/chain/consensus/filcns/upgrades.go
+++ b/chain/consensus/filcns/upgrades.go
@@ -2063,6 +2063,19 @@ func upgradeActorsV12Fix(ctx context.Context, sm *stmgr.StateManager, cache stmg
 		return cid.Undef, xerrors.Errorf("failed to perform migration: %w", err)
 	}
 
+	systemState.BuiltinActors = newManifest.Data
+	newSystemHead, err := adtStore.Put(ctx, &systemState)
+	if err != nil {
+		return cid.Undef, xerrors.Errorf("failed to put new system state: %w", err)
+	}
+
+	systemActor.Head = newSystemHead
+	if err = actorsOut.SetActor(builtin.SystemActorAddr, systemActor); err != nil {
+		return cid.Undef, xerrors.Errorf("failed to put new system actor: %w", err)
+	}
+
+	// Sanity checking
+
 	err = actorsIn.ForEach(func(a address.Address, inActor *types.Actor) error {
 		outActor, err := actorsOut.GetActor(a)
 		if err != nil {
@@ -2081,7 +2094,7 @@ func upgradeActorsV12Fix(ctx context.Context, sm *stmgr.StateManager, cache stmg
 			return xerrors.Errorf("mismatched address for actor %s: %s != %s", a, inActor.Address, outActor.Address)
 		}
 
-		if inActor.Head != outActor.Head {
+		if inActor.Head != outActor.Head && a != builtin.SystemActorAddr {
 			return xerrors.Errorf("mismatched head for actor %s", a)
 		}
 
diff --git a/chain/stmgr/forks.go b/chain/stmgr/forks.go
index 9d59b5428..8d1ac1dfb 100644
--- a/chain/stmgr/forks.go
+++ b/chain/stmgr/forks.go
@@ -178,16 +178,18 @@ func (sm *StateManager) HandleStateForks(ctx context.Context, root cid.Cid, heig
 	retCid := root
 	u := sm.stateMigrations[height]
 	if u != nil && u.upgrade != nil {
-		migCid, ok, err := u.migrationResultCache.Get(ctx, root)
-		if err == nil {
-			if ok {
-				log.Infow("CACHED migration", "height", height, "from", root, "to", migCid)
-				return migCid, nil
+		if height != build.UpgradeWatermelonFixHeight {
+			migCid, ok, err := u.migrationResultCache.Get(ctx, root)
+			if err == nil {
+				if ok {
+					log.Infow("CACHED migration", "height", height, "from", root, "to", migCid)
+					return migCid, nil
+				}
+			} else if !errors.Is(err, datastore.ErrNotFound) {
+				log.Errorw("failed to lookup previous migration result", "err", err)
+			} else {
+				log.Debug("no cached migration found, migrating from scratch")
 			}
-		} else if !errors.Is(err, datastore.ErrNotFound) {
-			log.Errorw("failed to lookup previous migration result", "err", err)
-		} else {
-			log.Debug("no cached migration found, migrating from scratch")
 		}
 
 		startTime := time.Now()
@@ -195,6 +197,7 @@ func (sm *StateManager) HandleStateForks(ctx context.Context, root cid.Cid, heig
 		// Yes, we clone the cache, even for the final upgrade epoch. Why? Reverts. We may
 		// have to migrate multiple times.
 		tmpCache := u.cache.Clone()
+		var err error
 		retCid, err = u.upgrade(ctx, sm, tmpCache, cb, root, height, ts)
 		if err != nil {
 			log.Errorw("FAILED migration", "height", height, "from", root, "error", err)
diff --git a/chain/vm/fvm.go b/chain/vm/fvm.go
index 901374a4f..47b4d3320 100644
--- a/chain/vm/fvm.go
+++ b/chain/vm/fvm.go
@@ -92,6 +92,15 @@ func (x *FvmExtern) VerifyConsensusFault(ctx context.Context, a, b, extra []byte
 		log.Info("invalid consensus fault: submitted blocks are the same")
 		return ret, totalGas
 	}
+
+	// workaround chain halt
+	if build.IsNearUpgrade(blockA.Height, build.UpgradeWatermelonFixHeight) {
+		return ret, totalGas
+	}
+	if build.IsNearUpgrade(blockB.Height, build.UpgradeWatermelonFixHeight) {
+		return ret, totalGas
+	}
+
 	// (1) check conditions necessary to any consensus fault
 
 	// were blocks mined by same miner?
diff --git a/miner/miner.go b/miner/miner.go
index 2d802e2cf..510ea4f0e 100644
--- a/miner/miner.go
+++ b/miner/miner.go
@@ -324,7 +324,7 @@ minerLoop:
 					"block-time", btime, "time", build.Clock.Now(), "difference", build.Clock.Since(btime))
 			}
 
-			if os.Getenv("LOTUS_MINER_NO_SLASHFILTER") != "_yes_i_know_i_can_and_probably_will_lose_all_my_fil_and_power_" {
+			if os.Getenv("LOTUS_MINER_NO_SLASHFILTER") != "_yes_i_know_i_can_and_probably_will_lose_all_my_fil_and_power_" && !build.IsNearUpgrade(base.TipSet.Height(), build.UpgradeWatermelonFixHeight) {
 				witness, fault, err := m.sf.MinedBlock(ctx, b.Header, base.TipSet.Height()+base.NullRounds)
 				if err != nil {
 					log.Errorf("<!!> SLASH FILTER ERRORED: %s", err)
diff --git a/node/impl/full/sync.go b/node/impl/full/sync.go
index 223f5c29e..4bf44363c 100644
--- a/node/impl/full/sync.go
+++ b/node/impl/full/sync.go
@@ -57,7 +57,7 @@ func (a *SyncAPI) SyncSubmitBlock(ctx context.Context, blk *types.BlockMsg) erro
 		return xerrors.Errorf("loading parent block: %w", err)
 	}
 
-	if a.SlashFilter != nil && os.Getenv("LOTUS_NO_SLASHFILTER") != "_yes_i_know_i_can_and_probably_will_lose_all_my_fil_and_power_" {
+	if a.SlashFilter != nil && os.Getenv("LOTUS_NO_SLASHFILTER") != "_yes_i_know_i_can_and_probably_will_lose_all_my_fil_and_power_" && !build.IsNearUpgrade(blk.Header.Height, build.UpgradeWatermelonFixHeight) {
 		witness, fault, err := a.SlashFilter.MinedBlock(ctx, blk.Header, parent.Height)
 		if err != nil {
 			log.Errorf("<!!> SLASH FILTER ERRORED: %s", err)